A transmission type HMD device that allows a viewer to view a virtual image overlaid on a scene is conventionally known (see, for example, Patent Literature 1). The HMD device is a display to be mounted on a head, and configured to project display light from a display to a user using projection optics or a light guide to allow the user to visually recognize a virtual image of a display image indicated by the display light. The user can visually recognize a virtual image by the HMD device overlaid on a real scene in front. Further, the HMD device can apply a technique called Augmented Reality (AR). That is, by displaying an AR image related to a real scene as a display image, information can be added to the real scene.
In addition, as an HMD device, technologies capable of changing an imaging position of a virtual image visually recognized by a user are disclosed in Patent Literatures 2 and 3. In the technique disclosed in Patent Literature 2, an imaging position of a virtual image is changed by mechanically switching an interval between a display panel and a magnifying optical member of a virtual image distance control unit. In the technique disclosed in Patent Document 3, an imaging position of a virtual image is changed by image processing by moving an emitting area of an image formed by display light from a pair of display drive units.